Study: HPV
vaccine is 100% effective

The first major
study of an experimental vaccine to prevent cervical
cancer found it was 100% effective, in the short term, at
blocking the disease and lesions likely to turn
cancerous, drugmaker Merck said Thursday.

Gardasil, a
genetically engineered vaccine, blocks infection by two of
the 100-plus types of human papillomavirus, HPV 16 and 18.
The two sexually transmitted viruses together cause
about 70% of cervical cancers. Other types of HPV also
can cause cervical cancer and painful genital or anal
warts. About 20 million Americans have some form of HPV.

The final-stage
study of Gardasil included 10,559 sexually active women
ages 16 to 26 in the United States and 12 other countries
who were not infected with HPV 16 or 18. Half got
three vaccine doses over six months; half got dummy
shots. Among those still virus-free after the six months,
none who received the vaccine developed cervical cancer or
precancerous lesions over an average two years of
follow-up, compared with 21 who got dummy shots.

“To have
100% efficacy is something that you have very
rarely,” said Eliav Barr, Merck’s head
of clinical development for Gardasil. “We’re
breaking out the champagne.”

The study, which
was funded by Merck, was to be presented Friday at a
meeting of the Infectious Diseases Society of America.

A second
analysis, including hundreds more women participating in the
ongoing study, showed that after just one dose the vaccine
was 97% effective. That analysis found only one of the
5,736 women who got the vaccine developed cervical
cancer or precancerous lesions, compared with 36 among
the 5,766 who got dummy shots. Barr said the 97% rate was
more “real world,” given that patients
sometimes miss or delay follow-up shots or tests.

“I see
this as a phenomenal breakthrough,” said Gloria
Bachmann, director of the Women’s Health
Institute at Robert Wood Johnson Medical School in New
Brunswick, N.J. Bachmann said diagnosis of infection leaves
women anxious over the heightened risk of cervical
cancer and raises questions among couples about
infidelity and prior sexual activity.

“You have
to get students [vaccinated] in grammar school, middle
school, high school before they become sexually
active,” she said.

Cervical cancer
is the second most common cancer in women and their
number 2 cause of cancer deaths, resulting in about 3,000
deaths in the United States and nearly 300,000 around
the world each year. At least half of sexually active
men and women become infected with HPV at some point.

The immune system
clears most such infections in a year or two, but
several types of HPV can persist, cause cervical cancer, or
trigger other cancers in the genital area. There is no
cure for HPV, but the cancers can be treated, and an
improved Pap test is catching more cervical cancer
before it has spread.

Station, N.J.–based Merck is seeking to beat rival
drugmaker GlaxoSmithKline to market with the first
cervical cancer vaccine. GlaxoSmithKline did not
return a call seeking comment but has published
research showing its vaccine against HPV 16 and 18 prevents
persistent HPV infection. The Merck vaccine also
reduces infection with HPV 6 and 11, which cause 90%
of genital warts cases.

Merck plans by
year’s end to seek Food and Drug Administration
approval to sell its vaccine for use by girls and
young women. “If all goes well, sometime in
2006 it should be on the market,” Barr said.

Merck is
continuing research on Gardasil and will soon report on four
years of follow-up on women in the current study. The
company also will explore whether the vaccine’s
effectiveness wanes over time. Barr noted that some
women in the study developed dangerous precancerous lesions
caused by HPV types other than 16 and 18. (AP)

Tags: Health, Health

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